Taiwanese Patent Publication No. 380471 discloses a conventional wrench including an annular head 20 and a grip 21 extending from the annular head 20. The annular head 20 defines a space 22, a recess 23 communicated with the space 22, a hole 24 communicated with the recess 23, a hole 25 co-centrically communicated with the hole 24 and a hole 26 eccentrically communicated with the hole 24. The space 22 partially overlaps the hole 24. A clutch is put in the recess 23. The clutch includes two claws 40 and a spring 43 between the claws 40. Each of the claws 40 includes a toothed face 41 and a rod 42. An annular gear 30 is put in the space 22. The annular gear 30 includes a toothed internal face 31 for engagement with a nut or a head of a bolt and a toothed external face 33 for engagement with the toothed face 41 of one of the claws 40. A positioning device 60 is put in the hole 26. The positioning device 60 includes a spring 61 and a ball detent 62. A disc 50 is put in the hole 24. The disc 50 includes a central hole 51 through which a bolt is driven into the hole 25. A recess 52 and two recesses 53 are defined in a lower face of the disc 50. The rods 42 are put in the recess 52. The recess 52 includes two opposite walls in contact with the rods 42. The ball detent 62 can be put in one of the recesses 53. A handle 54 is secured to the disc 50. However, the annular gear 30 is likely to escape the space 22 since it is retained only by means of a portion of the disc 50.
The present invention is therefore intended to obviate or at least alleviate the problem encountered in prior art.